The chain guide rail on the inside of the left bank has broken, gotten wedged between the cam gear and chain, jumping time. This invaribly bends several valves requiring a valve job to repair. The chain hasn't broken b/c the right cam is still in time allowing compression on the right bank. A ball end 8 mm allen socket is real damn helpful gettting the headbolts out. Gonna need 6mm allen hardware on several bolts along the way as well. A guide rail pin puller is real nice but not absolutely necessary. Other than that it's a lot of nuts and bolts. About 25-30 hrs worth of labor to have repaired at a shop.